I think that would be pretty awsome. Only attackable by the air. Battlefield 2142 had something like it called the Titan. Planetside2 could have one thats even better. Just a thought. I mean this is the future. They would have big command ships.
Link to full size: http://ukitakumuki.deviantart.com/art/PLANETSIDE-2-Pre-Viz-BASTION-FLEET-CARRIER-340427943